The Epistles of Paul the Apostle to the Thessalonians were written by Paul from Corinth about A.D. 52. These two letters are the earliest writings of the New Testament. Paul tells these Christians what sort of persons they must be, and that they must do their duty every day and not stand idle, waiting for the Second Coming.

2 Thessalonians 2

2:13 But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth: